Evolution.

[richard]

I'm afraid that I'm about to go on a bit of a pedantic tear, but a rather interesting post by naamaire inspired me to do it. It has come to my attention that many people, particularly those who subscribe to Creationist models, seem to misunderstand completely how the theory of evolution works. Those more knowledgeable than I about evolutionary biology may add information in the comments if they wish; I think that such a thing would be most useful.

I apologize for any incoherency, as well as typographical, orthographical and grammatical errors. It is late, and I am tired.

Many people misinterpret the theory of evolution; they seem to think that it has something vaguely to do with monkeys, or that it involves elephants' giving birth to hippopotami (or any other combination of a species giving birth to another). Those are gross oversimplifications; that is not the way in which evolution works at all. The theory of evolution describes gradual changes (and when I speak of gradual changes, I am speaking of changes that very well may take millions of years) in organisms that allow them to adapt to their environment. A dramatic change, like the elephants' giving birth to hippopotami that I gave in my example, would actually be antithetical to what evolution posits.

Organisms evolve through mutation and natural selection. Genes do not always copy themselves perfectly from parent to child; sometimes they mutate for no apparent reason. If the mutation happens to be adaptive, then the organism that harbours the gene will pass it on to its children, and if it is maladaptive, then the mutation will generally make sure that the organism does not live long enough to reproduce; therefore, such genes would not be passed on to the children. This would go on for quite a long time, making it very possible for new species to come about.

I should give an illustration so that my readers can understand better what I am talking about. I am sure that most of my readers are well aware of insects that evolve to be resistant to insecticides. When farmers apply such insecticides to their plants, those insects who happen to have (for whatever reason) a greater resistance to the pesticides will be more likely to survive and reproduce with each other, giving rise to more insecticide-resistant insects. Those who are not resistant will die. I know that many creationists will stop me there, and will try to call such evolution 'micro-evolution', which they admit exists, but will call larger-scale evolution (which is simply more 'micro-evolution' over a longer period of time) 'macro-evolution', which they dismiss. This is a fallacy; species tend not to come about during the course of human lifetimes. In fact, humans have been on Earth for rather a short time and have not had enough time to observe evolution directly, especially for large and complicated organisms like ourselves. Large-scale evolution does not happen in an instant. That we can see the sort of evolution observed in these insects is remarkable as it is.

The idea of organisms' suddenly giving rise to a newly evolved form and the argument about transitional forms' not being found are both utterly preposterous. Scientists do not believe this, and I am sure that they do not expect laymen to believe this, either. Of course a species only gives birth to its kind! It would be foolhardy to assume otherwise. Evolution's gradual nature, discussed earlier, makes that extremely improbable. Regarding the question of extant transitional forms, Richard Dawkins discusses transitional forms in an essay entitled 'Gaps in the Mind' in his book A Devil's Chaplain. He gives an example of transitional species in the form of the Herring Gull and Lesser Black-backed Gull ring.

The best-known case is the Herring Gull/Lesser Black-backed Gull ring. In Britain, these are clearly distinct species, quite different in colour. But if you follow the population of Herring Gulls westward round the North Pole to North America, then via Alaska across Siberia and back to Europe again, you notice a curious fact. The 'Herring Gulls' gradually become less and less like Herring Gulls and more and more like Lesser Black-backed Gulls until it turns out that our European Lesser Black-backed Gulls are actually the other end of a ring that started out as Herring Gulls. At every stage around the ring, the birds are sufficiently similar to their neighbours to interbreed with them. Until, that is, the ends of the continuum are reached, in Europe. At this point, the Herring Gull and the Lesser Black-backed Gull never interbreed, although they are linked by a continuous series of interbreeding colleagues all the way round the world. The only thing that is special about ring species like these gulls is that the intermediates are still alive. All (Dawkins' emphasis) pairs of related species are potentially ring species. The intermediates must have lived once. It is just that in most cases, they are now dead.
Richard Dawkins, 'Gaps in the Mind' from A Devil's Chaplain, p 22

Dawkins' example says it rather clearly. Transitional forms do exist.


I hope that this little write-up serves well in explaining how evolution works. If anyone has questions, do ask, and I shall either answer them myself, or point you to something that would answer the question for you.

Further reading
Richard Dawkins' The Ancestor's Tale
Richard Dawkins' The Blind Watchmaker
Daniel Dennett's Darwin's Dangerous Idea
TalkOrigins.org

Comments

[naamaire.livejournal.com]

Ahhh, and this explains why trees developed bark, as a defense against millions of years of animals with partially developed eyes bumping into them.

Seriously, though, I am simply trying to point out that evolutionary theory shouldn't be accepted as fact when it leaves so much unexplained. I remember when it was a proven fact that dinosaurs were cold-blooded, and then it was a proven fact that they were primitive mammals and the latest proven fact seems to be that they were primitive birds (or has that changed?)

If the theory of gravity could explain how some objects fall, but couldn't explain how others do, I wouldn't accept it either.

[crystalseraph.livejournal.com]

Any scientist worth their salt would never claim 'proof'. That's very much the domain of the media who takes this stuff and reports it to the public. Evolution is a theory, and that shouldn't devalue it. 'Religion as fact' is objectively far more tenuous as a theory than evolution is. They are both theories, of a sort. I'm inclined to go for the hundreds of years of study and accompanying mistakes and re-adjustments than the assurance of a book or three written before they understood the earth was round.

The theory of gravity isn't exactly linear as well, when you start getting into the nature of space-time xD

I guess the thing with that first comment (which made me snerk water on my desk) is that these animals wouldn't have bumped into trees: they would be living in habitats that suited their limited visual ability. If you're asking 'where do these species originally come from, to start evolving?', there's no simple answer. Basic lifeforms adjust and adapt to increase in complexity, and adapt specific traits to deal with their environment. A grex, for example, is an interesting look at what algae can evolve into when the need arises.

As to the dinosaur question, the current theory holds that dinosaurs, in their many species, were the berach between birds and reptiles. The older ones were more reptile-like, the later ones more bird-like. Vestigal feathers, complete feathers and extensive bird-like traits are found in late-Cretaceous period dinosaurs.

Complicated stuff, and I'm still really foggy-headed. Hopefully it makes some kind of sense xD

[naamaire.livejournal.com]

Actually, the idea that the bible was written by people who thought that the Earth was flat isn't true either. The Babylonian Talmud makes it clear that the Earth was known to be spherical, to hang unsupported in space, to orbit the sun, and to have seasons based on axial tilt for some thousands of years. In fact, I know of no time period in which it was widely believed that the Earth was flat. Columbus was not expected to sail off the edge of the world, he was expected to die of hunger before he reached India (which he would have had not the Americas gotten in his way. The fact is that he was wrong and those who spoke out against him were right, regarding the size of the Earth. It just so happened that there were a few more continents than were known of in Europe.)

[hms-beagle.livejournal.com]

Evolution isn't "fact," it just happens to be our current best explanation. Of course evolutionary theory will be reworked extensively, or perhaps even replaced, as we get more information. Just because it isn't perfect at this exact moment doesn't mean you shouldn't place *any* stock into it. I'm not trying to say dissent is bad (hell, it's what makes science science). But by that same token, if we didn't make some educated guesses and assumptions in science, we wouldn't get anywhere.

[phen0type.livejournal.com]

Indeed, and if evolution were as gapingly false as naamaire claims it to be, then the scientific community would not accept it, and creationists would have won Nobel Prizes and other such awards for disproving such a vast theory. Science constantly throws out old theoretical structures when more accurate ones are found. If there were any overhelming disproof against evolution, scientists would have discarded the theory.

Contrast this with dogma, in which adherents cling doggedly to a belief even after evidence to the contrary has been presented. There has been no actual disproof of evolutionary theory (although the theory has been refined over the years) - if there were, I would not accept it as an explanation for how our diverse species came to be.

[naamaire.livejournal.com]

So what is that divides people who accept dogma from those that reject it-- the fact that one group wears white coats and the other white collars? If scientists were immune to dogmatism, as you say, why then was Tesla censured-- he was right about alternating current and his peers should have recognized that fact. For that matter, the Bohr model of the atom, X-rays, the use of ether as an anesthetic, Einstein's relativity-- all of these things were initially rejected by the scientific community. Right now the evolutionary model is the dogmatism of the day, and more and more biophysicists are speaking out against it, often risking their careers to do so. So long as the grant money is controlled by people who grew up believing in Darwinism dissenting voices will be few and far between.

Of course the theory of evolution hasn't been disproven, that isn't the issue. The issue is that it hasn't been proven, but it is being taught as if it had. It is logically impossible to prove a negative, which is why the burden of proof is always on a new theory. I can't disprove alien abductions either, but that doesn't mean I am required to accept them as fact.

[phen0type.livejournal.com]

No.

Scientists need to see evidence. Although those things may have been rejected before, they have been accepted now, as you can well see. This is in sharp contrast to dogma, which never accepts new information. Theories are continually being thrown out in favour of new ones. Scientists are not like priests or government officials; someone who were to disprove such a large theory as evolution would be lauded for making a large discovery, not prevented from speaking.

No. There is evidence for evolution; there is none for alien abductions. One cannot conflate the two things at all.

[hms-beagle.livejournal.com]

Science isn't immune from dogma, but the difference between it and religion is that science isn't based on dogma.

Also, while of course it's healthy to have scientific dissent and challenge old theories, it's just as vital that we have people defend old theories if they think the theory is still valid. If we just rolled over and replaced all our theories with the first new ideas to come along, we'd be in deep trouble. Like you said, the burden of proof is on the new theory--which is why there are so many people defending evolutionary theory at the moment, because it has a pretty good bloc of evidence supporting it, and it's our current best idea. I don't think dogma has as much to do with it as you think (although I would be a right idiot if I tried to say dogma had NOTHING to do with it).

From my experiences, I haven't had any classes where evolution was touted as absolute fact. Almost every theory I hear about in class, evolution included, is prefaced (sometimes overly much) by the acknowledgment that nothing is proven in science, ever. But, as I've said, if they didn't at some point say, "For now, assume this is true," and move on, we wouldn't be able to get anywhere.

[phen0type.livejournal.com]

All of that makes perfect sense.

[sethrenn.livejournal.com]

Anyone who believes that science can't completely reform its view of a certain field if undeniable and overwhelming evidence is presented in favor of a new view, and that the entirety of a particular field of study will aggressively resist the new concept, needs to look at what happened with geology and the theory of plate tectonics in the late 1960s. It seems a bit bizarre from a modern perspective to envision a time when it was hotly debated whether continents did, in fact, move, but the idea that they never had was aggressively defended by people who didn't hold any kind of young-earth belief in the least.